Closure for alarm clocks or the like



May 9, 1967 J. M. WHITAKER ETAL 3,

CLOSURE FOR ALARM CLOCKS OR THE LIKE FiledOct. 22, 1965 lA/V'A/TOFJ. r01: 4/. lw/rmse 0044410 ,5. flearzmmv United States Patent'Ofilice 3,318,086 Patented May 9, 1967 The present invention relates to an improvement in the construction and assembly of alarm clocks and similar devices and more particularly to improved means for se curing a frame plate within a housing.

It is an object of the present invention to provide an improved closure for a clock or the like which permits secure locking in place of a frame plate within a housing but which avoids the use of mounting screws, brackets, pillars and the like which have usually been employed for fastening purposes in the past. It is a related object to provide a closure which employs bent tabs to provide engagement between a plate and the housing but which overcomes the disadvantages which have been thought to be inherent in the use of bent tabs. Specifically, the invention is directed toward a closure or locking arrangement for a clock structure which employs a particular tab configuration permitting the tab to be bent easily and quickly into a positive locking position by means of a simple twist of a suitable tool such as a screwdriver or the like but which, equally importantly, permits unlocking by simply reversing the procedure. It is a more specific object to provide a tab type locking arrangement for a clock or the like in which the tab movement is limited to avoid possibility of overstressing or breakage and which may be cycled through a number of operations, as may be required when the clock is repaired, with a high degree of reliability and little or no risk of breakage.

It is an object of the invention in one of its aspects to provide a novel closure for a clock, which, although easily accessible and readily actuated by a simple tool, occupies a hidden position behind the front edge of the clocks housing clock bezel so that the procedure to be used for disassembling the clock is not at all apparent, thus reducing the likelihood of tampering which might result in damage and tending to insure that any repair is carried out by an authorized person. It is a more specific object to provide a clock structure in which the integrity is further increased by including a lens of the recessed edge-locked type for overlying the dial plate and which must be intentionally deformed for removal and to provide access to the closure tabs.

It is yet another object of the invention to provide a closure locking arrangement for a clock plate or the like which is highly economical bothto make and to use and which is therefore particularly well suited for use on low cost units in a high quantity production line.

Other objects and advantages of the invention will become apparent upon reading the attached detailed description and upon reference to the drawings in which:

FIGURE 1 is a perspective view of a clock employing the present invention with portions of a dial plate broken away to show the mode of fastening, with the lens indicated by the dot-dash outline.

FIG. 2 is an enlarged fragment showing the securing tab construction.

FIG. 3 shows the structure of FIG. 2 in locking engagement, looking along the line 33 in FIG. 1.

FIG. 4 is a fragmentary perspective showing use of a tool to bend the tab into its extended position.

FIG. 5 is a section taken along the line 55 in FIG. 3.

FIG. 6 is a fragmentary section taken along the line 66 in FIG. 1 and showing the means for maintaining the dial plate captive.

While the invention has been described in connection with a preferred embodiment, it will be understood that we do not intend to be limited to the particular embodiment described but intend to cover the various alternative and equivalent arrangements included within the spirit and scope of the appended claims.

Turning now to the drawing there is disclosed a low cost alarm clock to which our invention is particularly applicable including a plastic housing 10 of one-piece molded construction having opposed walls 11, 12, a top 13 and a bottom 14 having integrally molded legs 15.

The housing includes an integral rear wall (not shown) having apertures for projection of the usual handsetting knob and alarm plunger. Since the back of the housing is enclosed the only access is through the front and the housing may be characterized therefore as one having a front opening.

Recessed in the front opening, and dimensioned to fit, is a metal front plate 20 from which extends a nest of shafts for mounting the usual set of indicating and setting hands 21. It will be understood that the mechanism which is coupled to the shafts is behind, and supported upon, the front plate 20. The hands cooperate with a dial plate 25.

In accordance with the present invention the wall of the housing is provided with an internal groove in alignment with the front plate 20 and the plate is formed with a slot along the edge thereof and defining a narrow tab having a region of attachment at one end and a region of reduced cross section at the center and with a pair of so that upon turning a tool in the slot the tab is twisted in the plane of the plate and swung edgewise into the groove for locking purposes. Subsequently, upon insertion of a tool and twisting in the opposite direction, the tab may be swung bodily out of the groove to free the plate. More specifically in accordance with the invention we provide a plate in which the tab portion has a region of connection with the plate at each end with a region of reduced cross section at the center and with a pair of tool openings so that the tab may be bellied out into the groove.

Thus, referring to the drawing, the plate 20 is provided with the tab 30 along an edge thereof, the tab being integral with the plate and having regions of connection at its ends 31, 32. The tab is defined by a slot 33 extending parallel to the edge of the plate. At its center, the tab has a region 35 of reduced cross-section preferably formed by a notch 36 which communicates with the slot. Opposite the tab 30 is a receiving groove 40 which may be conveniently molded in the wall of the housing. For moving the tab edgewise in both directions in the plane of the plate 20, between its locking and unlocking positions, tool openings 41, 42 are provided. Such tool openings are located between the region of connection and the region of central bending or reduced cross-section. Thus when a tool is inserted and twisted in the outward direction, as shown in FIG. 4, the tab is twisted, while remaining in the plane of the plate, from the original position shown in FIG. 2 to the bellied out position shown in FIG. 3. In the latter position the tab lockingly engages the groove in the wall of the housing so that the front or mounting plate cannot move either inwardly or outwardly. Since two slots are provided in the preferred embodiment, the tool is first used in one of the slots and then in the other. While the term a screwdriver has been shown for convenience and while a screwdriver will normally be the most convenient and available tool to accomplish the locking and unlocking function, it will be understood that the term tool is intended to be generic and that the slots 41, 42 may be of any configuration for insertion of a tool of a registering or complementary shape.

To facilitate bending, not only is the center of the tab structure made of reduced cross-section but, preferably, the regions of attachment 31, 32 are of reduced section by providing a smooth enlargement at each end of the slot 33 as shown. The smooth end contour of the slot avoids the concentration of stress which may occur where the tab is bent inwardly and outwardly repeatedly. Thus the tab structure may undergo a relatively large number of cycles, certainly adequate to take care of any repair of the clock during the course of its long life, without any danger of breakage.

Moreover, since the tab 39 is integrally anchored at its opposite ends, the outward movement must be accompanied by stretching of the metal forming the tab, and such stretching provides inherent self-protection against over twisting. That is to say, the metal, which is conveniently mild steel, is relatively strong in tension. Thus, as twisting occurs, tensile forces are built up in the center of the tab resulting in an increase in reactive force thus signaling to the operator by feel that a practical limit of twisting has been reached. This condition is particularly noticeable when performing the final twisting step with the tool inserted into the second opening of the pair.

While the invention has been described above in connection with a tab and cooperating groove along the left-hand edge of the plate 20, it will be understood that in a practical case similar structure will be provided at the opposite or right-hand edge, and corresponding reference numerals have been employed for both. If desired, the tabs may be used top and bottom, indeed, the present tab construction may be employed at all four of the edges of the plate 20 although this will normally not be necessary. However, where only two of the tab assemblies are used, for example along the side edges, support may be provided for the remaining edges in the form of internal ribs or embossments integrally molded in the housing and, for example, as indicated at 38 in FIGS. 1 and 6. Such auxiliary support obviates any tendency for the plate 20 to rock about an axis which includes the tabs.

In accordance with one of the more detailed features of the present invention a dial plate is provided in front of the front plate 20 not only to provide indicia for the hands but to conceal the tab structure and, in addition, a lens of box shape is provided dimensioned to fit into the front opening of the housing and mating with shallow grooves formed therein for holding the dial plate firmly in position against the front or mounting plate. Thus, as shown in FIGS. 1 and 6, we provide, in addition to the dial plate 25, a boxy lens 50 of transparent plastic having an inner edge 51 carrying a projection 52 which mates with a receiving groove 53 molded in the inner wall adjacent the front edge, or bezel portion, of the clock housing. Preferably the projections and grooves 52, 53 are provided at diametrica'l points on the lens structure.

Preferably also, the lens is formed of transparent molded plastic having inherent resilience such as polystyrene, causing the projections 52 to seat firmly in the receiving grooves.

The net result of the foregoing structure is to provide a composite locking means in which the mode of disassembly is effectively hidden and which thus tends to resist tampering. In the event that it is necessary for any reason to take the clock apart, strong fingertip pressure applied to the side edges of the lens will normally be sufiicient to press the lens side wall inwardly resulting in disengagement at the grooves 53. Or, if desired, the lens may be pried free by inserting a tip of a knife or other narrow edged instrument, indicated at 55, between the lens and side wall and applying a prying force. With the lens removed, the hands 21 are withdrawn from their respective shafts, permitting the dial plate to be lifted clear and exposing the tab structure. A tool inserted in the tool openings and rotated in the inward direction serves to straighten the tabs back to the condition shown in FIG. 2. This is done along both of the edges of the clock thus freeing the front plate 20 and the mechanism which is supported on it.

While the invention has been described in connection with a preferred embodiment, it will be understood that modifications may be made without departing from the broader aspects of the invention and with some sacrifice of the practical operating features. For example, the

- region 35 of reduced cross section, by increasing the depth of the notch 36, may be reduced to the point where the cross section equals or approaches Zero. Moreover, while the slot 35 which defines the tab has been shown parallel to the edge, the important thing is that it extends along the edge and it may, if desired, be arranged at an angle. Moreover, while the tab disclosed may be characterizcd as narrow, the term may be applied to any tab which does not encroach substantially into the area of the plate in which it is formed. Also, while the invention finds particular application to a housing having only a front opening for anti-tamper purposes or for reasons of economy, the invention may, if desired, be applied to a clock in which the rear is at least partially enclosed by non-integral means. While the term groove has been used in the claims, in referring to the recess 49 which receives the tab, it will be understood that the term is not necessarily limited to a recess having two side walls but applies equally to a recess or embcssment having a single side wall for actively obstructing the tab. Although the tab completely encloses the tool opening in the preferred embodiment, the opening may, with some sacrifice of integrity, be open at an end. Finally, it will be understood that while the invention has been described in connection with clocks, and particularly alarm clocks, it is not necessarily limited thereto and is equally applicable to similarly-housed small'mechanisr'ns which might be considered analogous to clocks. The term housing as used herein is a general term to denote supporting structure either of integral or multipart construction and either with or without a bezel portion or bezel surrounding a lens.

We claim as our invention:

1. In a clock or the like for manipulation by a tool, the combination comprising, a housing having an opening, a mechanism having a metal plate dimensioned to fit inside said opening substantially filling the same, said housing having a groove formed in theinside wall thereof in alignment with the plate, said plate having a slot extend ing along the edge thereof defining a narrow tab having a region of attachment at one end and a region of reduced cross-section spaced therefrom, said tab enclosing a tool opening intermediate the regions of attachment and reduced cross-section so that upon twisting of a tool in the slot the tab is bodily twisted in the plane of the plate and about its region of attachmentfor swinging of the tab edgewise into the groove in the housing for retention of i the plate therein and so that upon twisting of a tool in the opposite direction the tab is to free the plate.

2. In a clock or the like for manipulation by a tool, the combination comprising, a housing having an opening, a mechanism having a metal plate dimensioned to fit inside of said opening, said housing having a groove formed in the inside wall thereof in alignment with the plate, said plate having a slot extending along the edge thereof defining a tab portion, said tab portion being of reduced crosssection at its center and having tool opening in at least one side thereof so that upon twisting of a tool therein the tab portion is bellied out into the groove in the housing while remaining in the plane of the plate for retaining the plate in the housing and so that upon rotation of a tool in the respectively opposite direction, the tab portion is retracted from'the groove to free the plate.

3. The combination as set forth in claim 2 in which the structure is duplicated along opposite edges of the plate.

4. The subject matter of claim 2 in which the housing is provided with internal embossments adjacent the reswung outof the groove maining edges of the plate to prevent tilting of the plate with respect to the housing when the tabs are engaged.

5. In a clock or the like for manipulation by a tool, the combination comprising, a housing having a front opening, a mechanism having a metal front plate dimensioned to fit in recessed position inside said front opening, said housing having a groove formed in the inside wall thereof in alignment with the plate, said plate having a slot extending along the edge thereof defining a tab portion having at its ends regions of attachment to the body of the plate, said tab portion having a region of reduced cross-sectional area at its center and having tool openings on the respective sides thereof, said tab portion further having reduced cross-sectional area at the regions of attachment so that upon twisting of a tool in opposite directions in the respective slots the tab portion is bellied outwardly in the plane of the plate accompanied by 'bending of the metal at the regions of reduced cross-section for movement edgewise into locking engagement with the groove and so that upon reversing the procedure accompanied by bending in the opposite direction the tab portion is retracted from the groove to free the plate.

6. In a clock or the like for resisting tampering but capable of manipulation by a tool, the combination comprising, a housing opened at the front but enclosed on the remaining sides, a mechanism having a metal front plate dimensioned to fit in recessed position inside said front opening and having a set of nested shafts projecting therethrough for attachment of indicating hands, said housing having grooves formed in opposed inside walls thereof in alignment with the plate, said plate having slots generally parallel to opposite edges thereof defining narrow tab portions having at least one region of attachment to the body of the plate, each of said tab portions having a tool opening spaced from the regions of attachment so that upon twisting of a tool in said slots the tabs are twisted in the plane of the plate about the region of attachment for movement edgewise into the associated grooves in the housing, a dial plate dimensioned to fit over the front plate for concealing said tab portions, hands frictionally secured to the shafts for providing indication on the dial plate, a lens of box-shape dimensioned to fit in the front opening of said housing for holding the dial plate in place therein, said housing having additional groove means in opposed inside walls aligned with the inner edges of the lens, and mating projections on the inner edges of the lens for detented engagement in said groove means.

7. In a clock or the like for manipulation by a tool, the combination comprising, a housing having an opening, a mechanism having a metal plate dimensioned to fit in a recessed position inside of said opening, said housing having grooves along opposite inside walls thereof in alignment with the plate, said plate having slots along its opposite edges defining narrow tab portions adjacent said grooves, each of said tab portions having at least one associated tool opening so that upon twisting of a screwdriver tip in the slots the tab portions are twisted edgewise into the associated grooves for locking of the plate in the housing, said slots having end profiles which are smoothly contoured thereby to avoid concentration of stress at the region of bending.

8. In a clock or the like for manipulation by a tool, the combination comprising, a housing having an opening, a mechanism having a metal plate dimensioned to fit in a recessed position inside of said opening, said housing having grooves along opposite inside walls thereof in alignment with the plate, said plate having slots along its opposite edges defining narrow tab portions adjacent said grooves, each of said tab portions having surfaces engageable by a tool for applying torque to the tab portion in both directions in the plane of the plate for twisting the tab portion into and out of the associated grooves.

9. In a clock or the like for manipulation by a tool, the combination comprising, a housing having an opening, a mechanism having a metal plate dimensioned to fit inside said opening substantially filling the same, said housing having a groove formed in the inside wall thereof in alignment with the plate, said plate having a slot eX- tending along the edge thereof defining a narrow tab having a region of attachment at one end and a region of reduced cross-section spaced therefrom, said tab having an associated tool opening intermediate the regions of attachment and reduced cross-section so that upon twisting of a tool in the opening the tab is bodily twisted in the plane of the plate and about its region of attachment for swinging of the tab edgewise into the groove in the housing for retention of the plate therein.

10. In a clock or the like for manipulation by a tool, the combination comprising, a housing having an opening, a mechanism having a metal plate dimensioned to fit inside said opening substantially filling the same, said housing having a groove formed in the inside wall thereof in alignment with the plate, said plate having a slot extending along the edge thereof defining a narrow tab having a region of attachment at one end, said tab having a tool opening so that upon twisting of a tool in the slot the tab is bodily twisted in the plane of the plate and about its region of attachment for swinging of the tab edgewise into the groove in the housing for retention of the plate therein and so that upon twisting of the tool in the opposite direction the tab is swung out of the groove to free the plate.

No references cited.

RICHARD B. WILKINSON, Primary Examiner.

G. F. BAKER, Assistant Examiner. 

1. IN A CLOCK OR THE LIKE FOR MANIPULATION BY A TOOL, THE COMBINATION COMPRISING, A HOUSING HAVING AN OPENING, A MECHANISM HAVING A METAL PLATE DIMENSIONED TO FIT INSIDE SAID OPENING SUBSTANTIALLY FILLING THE SAME, SAID HOUSING HAVING A GROOVE FORMED IN THE INSIDE WALL THEREOF IN ALIGNMENT WITH THE PLATE, SAID PLATE HAVING A SLOT EXTENDING ALONG THE EDGE THEREOF DEFINING A NARROW TAB HAVING A REGION OF ATTACHMENT AT ONE END AND A REGION OF REDUCED CROSS-SECTION SPACED THEREFROM, SAID TAB ENCLOSING A TOOL OPENING INTERMEDIATE THE REGIONS OF ATTACHMENT AND REDUCED CROSS-SECTION SO THAT UPON TWISTING OF A TOOL IN THE SLOT THE TAB IS BODILY TWISTED IN THE PLANE OF THE PLATE AND ABOUT ITS REGION OF ATTACHMENT FOR SWINGING OF THE TAB 